The fabrication and assembly of solid oxide fuel cells (SOFCs), including both support and functional layers, remains one of the primary challenges preventing the widespread adoption of SOFCs as an energy conversion technology. SOFC structures produced using traditional manufacturing techniques are inefficient; the structural, non-functional, metallic components significantly contribute to the SOFC manufacturing time, design flexibility, and weight, which precludes the practical use of SOFCs in mobile applications such as transportation.
State-of-the-art methods for producing SOFCs typically involve separate processing of individual components, followed by assembly. Take the example of a planar solid oxide cell (SOC) stack that can be employed as either a fuel cell (SOFC) or an electrolyzer. The active components (cathode, electrolyte, and anode layers) are layered with interconnect plates (typically ferritic stainless steel plates with ceramic coatings). The interconnect plates provide an electrical path between cells, separating the fuel and air streams, and provide gas manifolds for fuel and air distribution. Gas channels are connected to gas manifold holes at the edges of the interconnect plates and cells to form a gas distribution network. Ferritic steel interconnect plates are used because of their low cost, good electrical conductivity, and machinability/formability to produce the gas distribution networks. However, there are serious drawbacks to this design. First, oxide scale formation on the metal surfaces and contamination of the cells by Cr from the steel. Second, the gas sealing that is used to form gas-tight oxidant and fuel flow networks is challenging. Third, massive end plates and bolts are needed to uniformly compress the cells, interconnect plates, and seals. And, the individual SOCs must be sufficiently thick for handling and assembly, leading to relatively high materials cost and concentration polarization losses in thick electrodes.